COMPARISON OF AMINO ACID POLYMERIZATION IN B. SUBTILIS AND E. COLI CELL-FREE SYSTEMS; HYBRIDIZATION OF THEIR RIBOSOMES

Abstract

The Bacillus subtilis is similar to the Escherichia coli system except that the ribosomes are fragile. A relatively poor response to poly U-directed polymeriza-tion of phenylalanine is observed. The initial rate of polymerization is only about 1/10 that in the E. coli system particularly at low con-centrations of poly U. The discrepancy is less pronounced at higher concentrations of poly U. Inactivity is due to a deterioration of the 30S fraction. If the 50S fraction of B. subtilis is mixed with the 30S fraction of E. coli, active ribosomes are obtained. More active ribo-somes may be prepared by mixing the 30S fraction of E. coli with the 70S fraction of B. subtilis due to an easy dissociation of 70S even in the presence of high Mg++. That hybridization had occurred was confirmed by P32- labeled E. coli 30S subunits. A protease-deficient strain [2-34] gave more active ribosomes when used freshly prepared; the ribosomes of this strain deteriorate on sucrose centrifugation due to inactivation of 30S particles, and active hybrids form between its 50S and E. coli 30S. A preselection of B. subtilis and E. coli ribosomes for the corresponding sRNA''s was observed.